Lyon midfielder Yoann Gourcuff is set for at least a month on the sidelines after tearing a hamstring, his club said Tuesday.

Gourcuff was forced off in the 47th minute of Saturday's damaging 2-1 defeat at home to struggling Nice -- a result which allowed Paris Saint-Germain to leapfrog Lyon at the top of Ligue 1.

The Lyon statement said Gourcuff will be out for four weeks and will undergo medical tests next week.

It was the 20th injury suffered by the 28-year-old, who will be out of contract in June, since joining Lyon in 2010.

He created a scandal against Nice as he left the field and returned to the changing rooms without informing either the referee or his team -- he has been accused several times of not caring about the team.

Maxime Gonalons, another Lyon midfielder, is also due to sit out the next four weeks after suffering a similar hamstring tear.

He has had to pull out of the France squad for friendlies against Brazil and Denmark later this week.